scholarly journals Differential anchoring effects of vaccination comparator selection: characterizing a potential bias due to healthcare utilization in COVID-19 versus influenza

2021 ◽  
Author(s):  
Anna Ostropolets ◽  
Patrick B. Ryan ◽  
Martijn J. Schuemie ◽  
George Hripcsak
Keyword(s):  
Influenza Vaccination ◽  
Large Scale ◽  
Index Date ◽  
Selection Procedure ◽  
Vaccine Safety ◽  
Selection Procedures ◽  
Safety Studies ◽  
Comparison Time ◽  
Baseline Characteristics ◽  
Study Designs

AbstractIntroductionObservational data enables large-scale vaccine safety surveillance but requires careful evaluation of potential sources of bias. One potential source of bias is an index date selection procedure for the unvaccinated cohort or unvaccinated comparison time. Here, we evaluate different index date selection procedures for two vaccines: COVID-19 and influenza.MethodsFor each vaccine, we extracted patient baseline characteristics on the index date and up to 450 days prior and then compared them to the characteristics of the unvaccinated patients indexed on an arbitrary date or indexed on a date of a visit. Additionally, we compared vaccinated patients indexed on the date of vaccination and the same patients indexed on a prior date or visit.ResultsCOVID-19 vaccination and influenza vaccination differ drastically from each other in terms of populations vaccinated and their status on the day of vaccination. When compared to indexing on a visit in unvaccinated population, influenza vaccination had markedly higher covariate proportions and COVID-19 vaccination had lower proportions of most covariates on the index date. In contrast, COVID-19 vaccination had similar covariate proportions when compared to an arbitrary date. These effects attenuated but were still present with a longer lookback period. The effect of day 0 was present even when patients served as their own controls.ConclusionPatient baseline characteristics are sensitive to the choice of the index date. In vaccine safety studies, unexposed index event should represent vaccination settings. Study designs previously used to assess influenza vaccination must be reassessed for COVID-19 to account for a potentially healthier population and lack of medical activity on the day of vaccination.

Differential anchoring effects of vaccination comparator selection: characterizing a potential bias due to healthcare utilization in COVID-19 versus influenza (Preprint)

2021 ◽  
Author(s):  
Anna Ostropolets ◽  
Patrick Ryan ◽  
Martijn Schuemie ◽  
George Hripcsak
Keyword(s):  
Influenza Vaccination ◽  
Large Scale ◽  
Index Date ◽  
Selection Procedure ◽  
Vaccine Safety ◽  
Selection Procedures ◽  
Safety Studies ◽  
Comparison Time ◽  
Baseline Characteristics ◽  
Study Designs

BACKGROUND Observational data enables large-scale vaccine safety surveillance but requires careful evaluation of potential sources of bias. One potential source of bias is an index date selection procedure for the unvaccinated cohort or unvaccinated comparison time. OBJECTIVE Here, we evaluate different index date selection procedures for two vaccines: COVID-19 and influenza. METHODS For each vaccine, we extracted patient baseline characteristics on the index date and up to 450 days prior and then compared them to the characteristics of the unvaccinated patients indexed on an arbitrary date or indexed on a date of a visit. Additionally, we compared vaccinated patients indexed on the date of vaccination and the same patients indexed on a prior date or visit. RESULTS COVID-19 vaccination and influenza vaccination differ drastically from each other in terms of populations vaccinated and their status on the day of vaccination. When compared to indexing on a visit in unvaccinated population, influenza vaccination had markedly higher covariate proportions and COVID-19 vaccination had lower proportions of most covariates on the index date. In contrast, COVID-19 vaccination had similar covariate proportions when compared to an arbitrary date. These effects attenuated but were still present with a longer lookback period. The effect of day 0 was present even when patients served as their own controls. CONCLUSIONS Patient baseline characteristics are sensitive to the choice of the index date. In vaccine safety studies, unexposed index event should represent vaccination settings. Study designs previously used to assess influenza vaccination must be reassessed for COVID-19 to account for a potentially healthier population and lack of medical activity on the day of vaccination.

Use of the self-controlled case-series method in vaccine safety studies: review and recommendations for best practice

2011 ◽  
Vol 139 (12) ◽  
pp. 1805-1817 ◽  
Author(s):  
Y. G. WELDESELASSIE ◽  
H. J. WHITAKER ◽  
C. P. FARRINGTON
Keyword(s):  
Adverse Events ◽  
Best Practice ◽  
Good Practice ◽  
Case Series ◽  
Vaccine Safety ◽  
The Self ◽  
Series Method ◽  
Safety Studies ◽  
Definition Of ◽  
Study Designs

SUMMARYThe self-controlled case-series method was originally developed to investigate potential associations between vaccines and adverse events, and is now commonly used for this purpose. This study reviews applications of the method to vaccine safety investigations in the period 1995–2010. In total, 40 studies were reviewed. The application of the self-controlled case-series method in these studies is critically examined, with particular reference to the definition of observation and risk periods, control of confounders, assumptions and potential biases, methodological and presentation issues, power and sample size, and software. Comparisons with other study designs undertaken in the papers reviewed are also highlighted. Some recommendations are presented, with the emphasis on promoting good practice.

scholarly journals Effect of Accessibility of Influenza Vaccination on the Rate of Childcare Staff Vaccination

2008 ◽  
Vol 29 (5) ◽  
pp. 465-467 ◽  
Author(s):  
Ingi Lee ◽  
Sarah Thompson ◽  
Ebbing Lautenbach ◽  
Leanne B. Gasink ◽  
Barbara Watson ◽  
...  
Keyword(s):  
Influenza Vaccination ◽  
Before And After ◽  
Baseline Characteristics ◽  
The Impact

We assessed the impact of free on-site influenza vaccination on childcare staff vaccination prevalence using 2 before-and-after studies. Vaccination was offered during the 2003-2004 and 2006-2007 influenza seasons. Staff vaccination prevalence was higher in each intervention season compared to the prior, nonintervention season. No baseline characteristics were associated with receipt of vaccination.

Influenza Vaccination Among Registered Nurses: Information Receipt, Knowledge, and Decision-Making at an Institution With a Multifaceted Educational Program

2008 ◽  
Vol 29 (2) ◽  
pp. 99-106 ◽  
Author(s):  
Cori L. Ofstead ◽  
Sharon J. Tucker ◽  
Timothy J. Beebe ◽  
Gregory A. Poland
Keyword(s):  
Influenza Vaccination ◽  
Registered Nurses ◽  
Educational Program ◽  
Medical Center ◽  
Vaccine Safety ◽  
Educational Interventions ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Vaccination Rates ◽  
To Receive

Objective.To evaluate the receipt of information and knowledge about influenza and vaccination, as well as influenza vaccination status and reasons for declining vaccination, among registered nurses.Design.Cross-sectional survey of registered nurses (RNs).Setting.A large tertiary medical center with a long-standing, multifaceted influenza vaccination program and relatively high vaccination rates among employees overall (76.5%).Participants.Randomly selected group of 990 RNs employed as inpatient staff nurses at the institution.Results.The survey was completed by 513 (51.8%) of 990 RNs. Most RNs (86.7%) had received an influenza vaccination in the past, and 331 (64.5%) intended to receive vaccination during the 2005-2006 influenza season. More than 90% of RNs acknowledged exposure to educational bulletins, and most had received information about influenza severity (383 [74.7%]), transmission (398 [77.6%]), vaccine safety (416 [81.1%]), and the time and location of free vaccination (460 [89.7%]). A majority (436 [85.0%]) felt they had received all the information they needed to make good decisions about vaccination. However, only 49 RNs (9.6%) gave correct answers to more than 85% of the knowledge questions on the survey. The reasons most frequently reported for declining vaccination were doubts about the risk of influenza and the need for vaccination, concerns about vaccine effectiveness and side effects, and dislike of injections.Conclusions.RNs exposed to a longstanding, multifaceted educational program had received information about influenza vaccination, but misconceptions were common and only 331 (64.5%) intended to receive vaccination. Strategies other than educational interventions are needed to increase influenza vaccination rates and thereby to ensure healthcare worker and patient safety.

A Methodology to Characterize Internal Solitons in the Ocean

2018 ◽  
Author(s):  
Henrique Coelho ◽  
Zhong Peng ◽  
Dave Sproson ◽  
Jill Bradon
Keyword(s):  
Internal Waves ◽  
Large Scale ◽  
Numerical Models ◽  
Phase Speed ◽  
Selection Procedure ◽  
Wave Theory ◽  
Tidal Energy ◽  
Internal Tides ◽  
Linear Wave ◽  
Soliton Generation

Internal waves in the ocean occur in stably stratified fluids when a water parcel is vertically displaced by some external forcing and is restored by buoyancy forces. A specific case of such internal waves is internal tides and their associated currents. These currents can be significant in areas where internal waves degenerate into nonlinear solitary waves, known as solitons. Solitons are potentially hazardous for offshore engineering constructions, such as oil/gas pipelines and floating platforms. The most efficient mechanism of soliton generation is the tidal energy conversion from barotropic to baroclinic component over large-scale oceanic bottom obstructions (shelf breaks, seamounts, canyons and ridges). In this paper, a methodology is provided to compute diagnostics and prognostics for soliton generation and propagation, including the associated currents. The methodology comprises a diagnostic tool which, through the use of a set of theoretical and empirical formulations, selects areas where solitons are likely to occur. These theoretical and empirical formulations include the computation of the integral body force (1), the linear wave theory to compute the phase speed and the empirical model proposed by (2). After the selection procedure, the tool provides initial and boundary conditions for non-hydrostatic numerical models. The numerical models run in 2D-V configuration (vertical slices) with horizontal and vertical resolutions ranging from 50 to 200 m and 5 to 10 m, respectively. Examples are provided for an open ocean location over the Mascarene Plateau in the Indian Ocean. Validation of diagnostics and prognostics are provided against ADCP and satellite data.

scholarly journals 'n psigometriese oudit op ‘n bestaande keuringsprosedure

2002 ◽  
Vol 28 (3) ◽  
Author(s):  
E. Cross ◽  
W. Marais ◽  
H. Steel ◽  
C. C. Theron
Keyword(s):  
Selection Procedure ◽  
Developmental History ◽  
Selection Procedures ◽  
Ideal Approach ◽  
History Of ◽  
Selection Of

The validity and credibility of assertions on the efficiency and equity of selection procedures is dependent on the methodology with which the procedure was developed and justified. An ideal approach to the development and justification of a selection procedure was derived from standard guidelines and operationalized in the form of a comprehensive checklist. A psychometric audit on the developmental history of the selection procedure for the selection of commission advisors was undertaken. Various shortcomings were identified and rectified or recommendations were made on rectifying them. The audit found that the selection procedure had zero validity, negative utility and discriminated unfairly. Opsomming Die geldigheid en geloofwaardigheid van uitsprake oor die effektiwiteit en billikheid van ‘n keuringsprosedure is ‘n funksie van die metodologie waarmee die prosedure ontwikkel en regverdig is. ‘n Ideale benadering tot die ontwikkeling en regverdiging van ‘n keuringsprosedure is uit standaard riglyne afgelei en geoperasionaliseer in die vorm van ‘n omvattende kontrolelys. ‘n Psigometriese oudit is onderneem op die ontwikkelingsgeskiedenis van ‘n keuringsprosedure vir die keuring van kommissie-adviseurs. Verskeie tekortkominge is geïdentifiseer en reggestel of aanbevelings ten opsigte van regstelling is gemaak. Die oudit het bevind dat die keuringsprosedure oor zero geldigheid beskik, negatiewe nutwaarde toon en onbillik diskrimineer.

Signal detection of adverse events with imperfect confirmation rates in vaccine safety studies using self-controlled case series design

2014 ◽  
Vol 56 (3) ◽  
pp. 513-525 ◽  
Author(s):  
Stanley Xu ◽  
Sophia Newcomer ◽  
Jennifer Nelson ◽  
Lei Qian ◽  
David McClure ◽  
...  
Keyword(s):  
Adverse Events ◽  
Signal Detection ◽  
Case Series ◽  
Vaccine Safety ◽  
Series Design ◽  
Safety Studies

Neuroimaging of Psychotic Disorders

2017 ◽  
Author(s):  
Stephan Heckers ◽  
Neil Woodward ◽  
Dost Öngür
Keyword(s):  
Blood Flow ◽  
Large Scale ◽  
Psychotic Disorders ◽  
Mental States ◽  
Brain Abnormalities ◽  
Cross Sectional ◽  
Risk Genes ◽  
Widespread Availability ◽  
Study Designs ◽  
Research Domain

Neuroimaging of psychotic disorders began in the 1970s with studies of brain structure, followed by studies of blood flow, glucose metabolism, and receptor chemistry. More recently, studies of functional activation, connectivity, and neurotransmission have been added. The widespread availability of MRI has liberated researchers from the constraints of postmortem research and the limitations of inferring brain abnormalities through neurochemical effects in plasma or urine. Neuroimaging researchers aim to establish diagnostic markers, explain abnormal mental states, test anatomical and neurochemical models, and study the association of risk genes with brain abnormalities. Most studies have been cross-sectional and limited in size. But the ability to assess patients longitudinally and with large-scale study designs will ensure a prominent position for this research domain in the study of psychotic disorders.

A comparison of the Holstein Friesian and Norwegian cattle breeds for milk production at two levels of nutrient intake

2001 ◽  
Vol 2001 ◽  
pp. 38-38 ◽  
Author(s):  
T.W.J. Keady ◽  
A.D. Crawford ◽  
C.S. Mayne
Keyword(s):  
Food Intake ◽  
Milk Production ◽  
Selection Procedure ◽  
Dairy Herd ◽  
Animal Performance ◽  
Nutrient Inputs ◽  
Selection Procedures ◽  
Holstein Friesian ◽  
Nutrient Utilisation ◽  
Breeding Programmes

Breeding programmes for Holstein Friesian (HF) animals have been based on improved milk production with little emphasis on functional traits such as fertility. This has resulted in a rapid increase in milk production potential of the national dairy herd but unfortunately this has been at the expense of issues such as longevity, especially due to poor reproductive performance. In contrast Norwegian (NC) dairy cattle have been bred via a multi-trait selection procedure for 25 years and there is evidence that fertility has improved during that period. These differences in selection procedures for the two breeds may have major effects on overall herd output and profitability within the grass-based systems of milk production employed in Northern Ireland. The present study is part of an overall study comparing the effects of HF and NC genotypes on food intake, animal performance, nutrient utilisation, behaviour, health, fertility and longevity. The objective of the present paper is to present the effects of breed on food intake and utilisation, and animal performance when offered two levels of nutrient inputs based on grass silage-based diets.

The effect of two levels of nutrient intake on milk production of two dairy cow genotypes

2002 ◽  
Vol 2002 ◽  
pp. 12-12 ◽  
Author(s):  
T.W.J. Keady ◽  
C.S. Mayne
Keyword(s):  
Dairy Cattle ◽  
Milk Production ◽  
Dairy Cow ◽  
Nutrient Intake ◽  
Selection Procedure ◽  
Nutrient Input ◽  
Selection Procedures ◽  
Grass Silage ◽  
Holstein Friesian ◽  
Breeding Programmes

Breeding goals differ for different breeds of dairy cattle. For example the breeding programmes for Holstein-Friesian (HF) animals have been based primarily on improved milk production with little emphasis on functional traits such as fertility. In contrast, Norwegian (NC) dairy cattle have been bred using a multi-trait selection procedure for 25 years. These differences in selection procedures for the two breeds may have major effects on overall herd output and profitability with the forage-based systems of milk production employed in Northern Ireland. The objective of the present paper is to present the effects of two levels of nutrient input on food intake and utilisation, and animal performance of the two breeds, with diets based on grass silage during the first and second lactation.

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